Increasingly drugs are dispensed as a mist for inhalation. Not only is this used for asthma drugs, but it is used for other drugs as well. Asthma drugs have been dispensed by a nebuliser, which provides a mist for inhalation by successive breaths. Increasingly, nebulisers are being replaced by pressurised metered dose inhalers. The former are bulky, expensive pieces of equipment, whilst the latter are disposable aerosol devices but they suffer from some disadvantages. In particular, inhalers require a deep breath to ensure that the medicament is carried into the lungs. Patients, in particular infants, young children and those with severe symptoms, having weak breathing may be unable to use an inhaler effectively and have to rely on a nebuliser.
Conventionally, aerosol storage devices have utilised a metal can for storage of the contents to be dispensed under pressure contained in the can. However, it is anticipated that in the future metallic cans may be replaced by cans of plastics material or even of glass for specialised applications. Accordingly as used herein the term “can” means not only metallic cans but substitute or equivalent containers of other materials, in particular glass and plastics materials.